Fine grinder



H. M PLAISTED.

FINE GRINDER.

APPLICATION FILED MAR. 21, 1919. 1A18fi359 Patented une 6, 1922.

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FINE GRINDER. APPLICATION FILED MAR. 21, 1919- Patented June 6, 1922.

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HAROLD IVL-PLAISTED, or ST. LOUIS, MISSOURI, ASsIGNoR or FORTY-NINE ONE- HUNDREDTHS To WILLIAMS PATENT CRUSHER & .PULVERIZER COMPANY, or ST. LoUIs, M SsaUnI, A CORPORATION or MISSOURI.

FINE GRINDER.

Specification of Letters Patent. Patgntgd June 6, 1922,

Application filed March 21, 1919. Serial No. 283,977.

To all whom it may concern:

Be it known that I, HAROLD M. PLAISTED, a citizen of the United States, residing at St. Louis, State of Missouri, have invented certain new and useful Improvements in Fine Grinders, of whichthe following is a specification.

This invention relates to certain new and parts, Fig. 1 represents a vertical sectional elevation across the shaft-of a grinder exemplifying my invention; Fig. 2 a vertical sectional elevation of said machine taken on the line 2-2 of Fig. 1; Fig. 3 a side elevation of said machine with the shaft bearing removed and part of the housing of said bearing in section and Fig. 4 a front view of said grinder with part of the casing broken away to Show the breaker plate:

The letter A designates a rotor shaft driven by a pulley B and mounted in suitable bearings, such as ball bearings shown in Fig. 2, secured in a ring housing C contained within a clamp D carried by the side housing E of a grinder of suitable construction.

On the shaft A are mounted discs F, in which are pivotally mounted stirrup hammers having legs G provided at their inner ends with holes for pivot bolts H passing through, holes in said disc's F. The said legs are connected by across bar, forming the head C of the hammer the outer surface I of which forms part of a cylinder and is described by an arc the center of which is the pivot point of support for said hammer. The inner surface J of the cross bar is likewise convexe'd preferably, but] reversely curved, and the inner surface and outer surface or faces of the cross bar, or head C meet each other at intersecting lines forming cutting edges K K at equal distances A double convex section is thus formed of considerable thinness radially, relative to its breadth from edge to edge, whereby the hammer head C formed by this cross bar is practically all edge at front and rear; in other words, it does not present to the material ,within the grinder a blunt face, as in the usual form of hammers, but on account of its relative thinness radially and the lenticular form of cross section it passes through the material with minimum resistance, and consequently requires comparatively little power to effect the rotation of a rotor having this form of hammer.

A breaker plate L is mounted in a pocket L formed in the front of said casing, with openings m at the sides whereby the breaker plate may be slipped into said pocket from one or either side. The length of the breaker plate is practically the width of the housing, and therefore the ends of the breaker plate bear upon the edges of the openings in the sidesof the housing. If desired the upper edge of the plate may have a lip l fitting a matching opening or groove in the top of said pocket.

Cooperating with said breaker plate is a cage M, preferably solid and without openings, and fitting in corresponding openings in the side housing of the grinder. The cage is nearly semi-circular, as shown 1n Figs. 1 and'Q, and a tapered key 0 1s drlven in from one or both sides of the housing into the clearance spacebetween the adjacent edges of the breaker plate and. cage, whereby the plate is forced upward and the cage is forced downward, and both are firmly held in operative position.

The hammers are so mounted that their outer faces I are in close proximity to the cage M along a line in saidface parallel tothe shaft. Since the outer face is cylindrical about a shorter radius than the grind- I ing face of the cage, this face I Wlll present opening between the outer face I and the grinding surface of the cage M will allow the entrance of the coarse feed, and by the wedging action, cause the pivoted hammer to be retarded and thus crush the interposed feed material between the face I and the cage as indicated in Fig. 1. Any material that is not thus wedged between the crushing surfaces, passes over the inner face of the hammer and is met by the follow.

ing hammer. It will be noted that there is always a line in the outer face I parallel to the shaft, that is in close proximity to the grinding cage, and that that line or'element in the face shifts back and forth from the center of the face to the forward point under the action or retarding influence of the mate rial wedged between the cage and said outer face. Thus the jaw action or jaw crushing action, is obtained by the rotary pivoted hammers and their outer cyl ndrical faces in connection with the cage in close proximity to the hammer circle. lVhile I have shown the cage as solid, it may be otherwise formed, and I have shown in Figs. 1 and 2 a hammer head having openings P preferably parallel to the radial plane and extending from the outer face I to the inner face J with increasing size or distance between the passages, whereby clearance passages are formed for the relief of the material being crushed at the outer face.

This material, thus crushed, will pass through said passages, as indicated in Fig. 1 by the fine material. This open bar construction of the cross bar head C of the hammers acts in substantially the same way as a cage with open bars,that is, the material being crushed is released from the crushing area and thus avoids clogging of the hammer and cage with surplus material or material already ground to the proper degree of fineness.

It is now my aim to withdraw such fin ished product from the grinding cage and action of the rotor, and this I do by the construction. shown in Fig. 1, in which a back wall Q is provided with a passageway R near the junction of the curved top S; and side walls T combine with said top and back wall and a bottom U of ahopper V, to form a receiving chamber X back of and partly below said hopper. The wall U of said hopper is inclined and preferably tangent to the hammer circle, and is provided.

on its lower end with a grinding plate WV concentric with the shaft A. The upper end of said bottom is hinged or pivoted at 3 adjacent to the top S so that the lower end with. its grinding plate W may be adjusted to and from the hammer circle by means of rods 4, each having one end secured to the bottom end of the hopper bottom U and the other end passing outward through openings in theouter wall 5 of said hopper, and having jam nuts 6 by which the rod 4 is firmly held by a stirrup frame 7 from the front wall of the hopper casing. The joint between the curved top S and the hopper bottom U is filled with a fibrous or flexible material 8, so that the slight movement at mg. haust chamber 9 is formed by walls back of and adjacent to the curved top S and a communicating passage from said lateral chamber connects with said opening R in the back wall Q. This lateral chamber 9and passage 10 which is a continuation ofthe passageway R are connected by pipes 11, preferably at each end of said chamber 9, to a fan exhaust or other suction means not shown. A certain amount of air will enter with the feed through the hopper V but it is desirable to provide a regulated air inlet by which the quantity of air, depending upon the weight of the material being ground, may be varied. This is effected by providing a closing plate in duplicatev having matching holes. The inner plate 12 is divided in half through the axis of the shaft, and is preferably circular and a little larger than the opening 13 in the side housing or the casing of the grinder so it will overlap said casing as shown in Figs. 2 and 3. The lower half of the plate preferably fits in groove 14 in the lugs 15 of said housing clamp D, and the outer plate 16 is somewhat smaller in diameter so it will fit between said lugs 15 as shown in' Fig. 3 and be readily rotated by means of a handle 17 at the periphery of said plate, preferably formed by the turned The reason of this is, that a lateral exout end of the splicing strip 18 fastening together the halves of said outer plate. Holes 19 and 20 are provided in the outer and inner plate respectively, and the rotation of the outer plate will vary the effective opening for air inlet. The opening 13 1n the side of the casing is slightly larger than the diameter of the discs F which are mounted directly adjacent to said openings and practically close the casing to the exit of material. In these discs are likewise provided holes 21 as near the center as prac ticable, by which the air admitted through the side closing plates with their regulated openings passes to the center of the rotor between the discs at both sides. This interior space between the discs is filled with material being ground, and the finer or finest particles will be carried upward by the suction of the air entering through the reguthe hopper bottom U for further grinding action by the hammers, and especially by the fine grinding plate W that is closely adjusted to the hammer circle.

The chamber X above the rotor as thus described, is preferably provided with inclined partitions 22 and 23 nearly parallel to the hopper bottom U, and having on their bottom ends grinding plates or other concaves 22 and 23', substantially concentric with the axis of the. rotor. These bottom ends are provided with side extension lugs 24, fitting in matching grooves 25 in the sides of the casing, which casing 1s spaced nearer together above the rotor than below the center of the rotor, so that said grooves 25 are open at the bottom for receiving said lugs 24. A sliding adjustment of said partitions and grinding plates is effected by means of rods 26, preferably fastened at their upper end and passing outward through the curved top and having on their threaded outer ends adjusting nuts 27, mounted in slotted extensions 28- from the top of the casing. Since the grinding plate W is substantially tangent to the hammer circle at one'side of the rotor, the partitions 22 and 23 provide return passages for the coarser material driven upward by the hammers, which passes around the upper ends of the partitions which do not extend upward to the curved top but leave a space as shown in Fig; 1. The coarser particles are therefore deflected by the curved top over the edge of said partitions and pass downwardagain to the rotor, and are delivered to the hammers as they pass below the lower end, and'crush between the grinding concaves and the hammer faces I. The outlet or lower ends of said passages are reduced in size as shown in Fig. 1, so as to deliver the returning stream of particles in a thin line across the faces I of said hammers. The hopper bottom U is provided with an adjustable slide 29, by which the outlet or throat V of the hopper V and therefore the entrance of the material to the rotor is regulated. It will be observed that the hinge or swinging adjustment of the hopper bottom U, does not prevent the adjustment of the cut-off slide 29 mounted thereon, as suitable slots are provided opposite the adjusting rods 4 at the sides of said plate.

By means of the wider spacement of the sides of the casing below the center and the projections formed by said'sides being nearer together above the rotor, I am. able to slide the projecting lugs 24 of the grinding plates 22 and 23 with the partition plates and adjusting rods attached thereto, upward into sliding engagement with the grooves 25 in the sides of the casing. Other operative means for adjusting said grinding plates and partitions may be employed.

The duplicate closing plates 12 and 16 in the sides are retained in position by clips 30 as shown Fig. 3. The back or rear end of the cage is also provided with an adjustment, such as screws 32 passing through the back wall and engaging the cage, whereby the adjustment of the screws from. outside will force the rear end of the cage inward toward the hammer circle and.tal(e up the clearance space that is shown in Fig. 3 on the inside of the cage. This adjustment and therefore the space at the back end of the cage, is very slight and barely more than is necessary to bring the rear end of the cage 'into contact with the hammers or tangent to the hammer circle. Slight as this adjustment may be, it Will provide a fine grinding action at the rear of the cage similar to that of the concave grinding surfaces V, 22 and 23.

The means for regulatingv the size of the outlet R in the back wall of the mainchamber preferably in the form of a cut-off slide 31, provided with holes and pin for adjusting said slide to various positions particles, passing upward along the back wall past the opening therein. The openings l9 and 20 communicating with the openings 21 in'the discs, admit any desired quantity of air to'the inside of the rotor and consequently provide a -re'gulatable quantity ofair to correspond with the fineness and weight of the material being ground and thus pneumatically removed from the grinder. In other words, a heavy material will require more air to carry it upward and outward into the, pipes 11 than a lighter material and the air inlet would be correspondingly large and the velocity of the air at the outlet of the main chamber -would be regulated by the slide31 to act with best effect upon this heavyv material. On the other hand, a light material compared with the one just described, would allow of the reductionof the quantity of air by closing the regulating side plates more or less to give sufficient air to lift the relatively lighter material, and then the slide 31 would be adjusted to secure the proper velocity of air at the outlet to suck out the fine particles of such lightrmaterial from the main chamber, while leaving the heavier particles of the same material to pass upward over the upper ends of the par tition walls 22 and 23 and downward through the constricted openings andupon the grlnding faces I of the rotating ham-.

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both the quantity of air admitted to the casing and the veloci y of the air escaping under suction from said casing, according to the weight and fineness or either, of the material being ground.

I claim:

1. In a grinder provided with a cylindrical cage, having a rotor mounted therein, hammers mounted in the rotor, said hammers terminating at their free ends in heads hav ing convex inner and outer surfaces, said outer surface being disposed substantially tangent to the inner surface of the cage.

2. A. fine grinder comprising a cylindrical cage, and rotary pivoted hammers mounted therein, each having a cross bar connectin two legs provided with holes for pivoted mounting,said bar having an outer cylindrical face and aninner reversely curved face meeting the oute face in a cutting edge at each side of a radial line, and having radial openings between said faces forming passages for the escape of material crushed between said outer face and the cage.

3. In a grinder provided with a casing having therein a feed hopper, a rotor within said chamber, a chamber above said rotor and within said casing for receiving ground mate rial, means within the chamber for separating the finely ground material from the coarsely ground material and returning the latter to the rotor, and grinding plates adjacent to the bottom of said chamber for further grinding the returned material.

4. A fine grinder comprising a rotor hammer element, a hopper having an inclined bottom substantially tangent to said rotor hammer circle at the lower end and pivoted near the upper end, a cut-off slide adjustably mounted on said hopper bottom, and means to adjust the lower end of said slide and hop per bottom to and from said hammer circle.

'5. A fine grinder comprising a rotor, a casing, a hopper having a bottom wall, a back wall sidewalls and curved top wall forming, in'combination with said hopper bottom wall, a chamber above said rotor, in clined partition walls substantially parallel to said hopper wall and provided with grind ing concaves at their lower ends adjacent to the hammer circle and forming a series of return passages for the material deflected by the curved wall, and means extending out side said chamber to adjust said partitions and grinding concaves with regard to said hammer circle. j

6. A fine grinder comprising a rotor, a casing having side and top walls forming a hopper and a main chamber below said hopper and above the rotor,--the back wall having an opening near the curved top,-

walls forming a lateral chamber and comopening in the back wall with the main chamber, a regulating cut-0H slide at said passage, and pipes under air suction connected to said lateral chamber.

7. A fine grinder comprising a rotor shaft, discs thereon, stirrup hammers pivotally mounted on said discs, a casing having openings in the sides and air suction means communicating therewith,said discs being mounted at said openings and practically closing same to the exit of material, and having openings near the shaft for air inlet, and side closing plates having adjustable openings for air inlet.

8. A fine grinder comprising a rotor, a casing having its sides spaced nearer together above than below said rotor and grooves, open below, formed on the inside above the rotor, walls forminga chamber above said rotor, slidable partitions having grinding plates provided with lugs mounted in. said grooves, threaded rods extending from the top of said slidable partitions through the top of the casing and operable from outside the casing for adjusting said partitionsand grinding plate.

9. In a grinder provided with a cylindrical cage having a rotor mounted therein, hammers mounted in the rotor, said hammers terminating at their free ends in heads,

the outer surfaces of which are convex and disposed substantially tangent to the inner surface of the cage.

10. In a fine grinder, a rotor provided with hammers havin heads of double-convex crosssection, sai heads being perforated radially from the outer convex surface to the inner convex surface.

11. In a rotary grinder, a housing provided with a hopper, a cage co-operating with the housing, a breaker plate adjacent the throat of the ho per, a rotor, and a receiving chamber above t e rotor, said chamber being provided with partitions, each of which terminates in a grinding plate adjacent the rotor.

12. A disintegrating device, consisting of a concave having a rotor therein, said rotor having hammers with heads having convex outer and inner surfaces terminating in cut ting edges, and said outer convex surface being on an arc of less radii than that of the concave.

13. In a grinder, a rotor provided with hammers having heads of double convex cross-section and a shank having an opening for pivotal mounting, the radius of curvature of the outer convex surface being described from the shank opening, and the radius of curvature of the inner convex surface being substantially greater than that of said outer convex surface.

' In testimony whereof I have afiixed my signature. HAROLD M. PLAISTED. 

